Women & Allergies/Asthma

Hormones have a varied and unpredictable influence on the immune system.  Naturally occurring fluctuations in hormones occur during the menstrual cycle, menopause and pregnancy.  Each hormonal stage can lead to flaring of allergies and asthma.    External sources of hormones (such as oral contraceptives (“the pill”) may be therapeutic while in others they may instead be the culprit.

Menstrual Cycle Can Worsen Asthma

Premenstrual or menstrual flare of asthma occurs in about 1/3 of female asthmatics.  Regulation of the cycle with oral contraceptives is helpful in some patients but any decision to start hormone therapy should only be made after careful consideration of all risks and benefits.

Pregnancy’s Impact on Asthma

The risks of uncontrolled asthma are far greater than the risks to the mother or fetus from the medications used to control asthma. It is important to have the asthma under good control: breathing difficulties in the mother affect the fetus by compromising the oxygen supply. When asthma is controlled, women with asthma have no more complications during pregnancy and labor than other women. However, uncontrolled asthma during pregnancy can produce serious maternal and fetal complications. Uncontrolled asthma is associated with complications such as:

  • premature birth
  • low birth weight
  • maternal blood pressure changes (which may be very serious)

Many allergy and asthma medications are considered relatively safe in pregnancy. If you are a woman of child-bearing age and planning a pregnancy, review all of your medications with your doctor before, or as soon as possible into pregnancy. Inhaled steroids are generally considered safe and effective. They are considered safe for pregnant women and their babies, according to a 1999 study, although pregnant women taking both beta2-agonists and corticosteroids are at higher risk for diabetes during pregnancy (gestational diabetes).

Breastfeeding Issues

In general few medications are contraindicated for use during lactation. Most medications do pass through to breast milk but usually in very small amounts (less than 1% of the adult dose). There may be some slight concern that antihistamines may reduce the amount of milk produced. Infants of mothers taking sedating antihistamines or decongestants could be slightly drowsy or irritable. Inhaled steroids (nasal or asthma sprays) are probably safer than pills.


A Danish study compared twins in which one had asthma and one did not. Major findings were that:

  • that it look longer for asthmatics to get pregnant (whether or not they were allergic)
  • Untreated asthmatics took longer to become pregnant than treated asthmatics (including those on inhaled steroids)

How could asthma affect fertility?
Asthma is not just a disease of the lungs, there are systemic features (including higher levels of allergic cells, known as eosinophils, in the blood)

In summary:
Both treated and untreated asthmatics appear at higher risk for subfertility (taking more than 1 year to become pregnant).   Is that simply a marker for asthma severity?   It is not clear but one thing is certain:  taking care of asthma is very important during a pregnancy so in anticipation of that, asthma care should be started and optimized.

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